Safety binding heelpiece for skis

ABSTRACT

A heel unit (10) of a safety ski binding comprises a unidirectional blocking arrangement (60&#39;) with at least one blocking member (62&#39;) arranged between a sole holder (16) and a spring biased return cam (26). The unidirectional blocking arrangement blocks in the opening direction and is releasable against a slight spring force (66) by means of a manual release member (64). One of the return cam (26) and the sole holder (16) is provided with a bearing face (68), generally circular or semicircular and concentric to the axis (A) of the return cam and of the sole holder for the blocking member (62&#39;) which is permanently resiliently urged into an actual blocking position.

BACKGROUND OF THE INVENTION

The invention relates to a heel unit for a safety ski binding,comprising a base body intended to be fixed to a ski, a return camrotatably mounted on the base body about an axis and returned by aspring device into a rotary starting position, a sole holder rotatablymounted about the same axis, and a unidirectional blocking arrangementarranged between the return cam and the sole holder and comprising atleast one blocking arrangement, said blocking arrangement being blockedin the opening direction and being releasable against a slide springforce by means of a manual release lever.

Heel units of this kind can be opened for example by means of a manualactuation lever with a minimum effort, by firstly decoupling the soleholder from the spring arrangement which normally urges the sole holderin the closing direction. During such a manual release process, the soleholder can thereby be pivoted into the opening position without havingto overcome for this purpose the relatively high return force exerted bythe spring arrangement. As soon as the heel unit is closed again and theforced closure is again established between the sole holder and thespring-urged return cam, the heel unit fulfills again the usual holdingfunction and simultaneously allows a reliable safety release.

In a heel unit known from DE 26 28 748 A1, a snap member urged by thespring arrangement engages a slide rail provided with a culminatingpoint, the slide rail being provided on a swing arm concentric to thesole holder. In a starting rotary position corresponding to the closingposition, the swing arm and the sole holder contact each other along acircular path eccentric with respect to the pivot axis. A ball lockprovided on the swing arm is active between the latter and the soleholder, and locks when the sole holder is urged in the openingdirection, provided that the sole holder has already reached itsstarting rotary position with respect to the swing arm. The ball lockcan be released by means of a manual actuation lever.

The drawback of these known heel units is the forced closure necessarybetween the swing arm and the sole holder for holding the sole until thesafety release can no longer be ensured for even small displacements ofthe starting relative rotary position of these two components of theheel unit. In other words, the ball lock does not block anymore becauseof the distance which appears between the swing arm and thecounter-surface provided on the sole holder. This distance increases asa function of the actual variation of the starting relative rotaryposition. Consequently, if the sole holder is not completely downwardlyengaged, for example because of the formation of ice on the surface ofthe ski or because of an over-standard sole thickness, it can happenthat the required blocking is not guaranteed.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide an improved heelunit for a safety ski binding of the kind mentioned at the beginning,which can readily and reliably also always be closed while permitting amanual or arbitrary release with a reduced effort. Thus, the desiredreturn or holding function is ensured, even if the sole holder urged inthe closing direction does not reach a predetermined final position,while also ensuring a reliable safety release.

In order to solve this problem, the invention provides that one of thereturn cam and the sole holder is provided with a bearing face, which isgenerally circular or semicircular and concentric to the axis of thereturn cam, and of the sole holder for the blocking member, which ispermanently resiliently urged into an actual blocking position betweenthe return cam and the sole holder. The blocking member is supported ina force-locked manner on this bearing face when the sole holder is urgedin the opening direction, and permanently engages this bearing facewithout force transfer when the sole holder is urged in the closingdirection, substantially independently of the actual rotary position ofthe sole holder relative to the return cam, thereby allowing a relativedisplacement substantially without effort of the sole holder withrespect to the return cam in the closing direction.

Owing to the invention, since the circular or semicircular bearing faceis made concentric to the axis of the cam and of the sole holder, theblocking member resiliently urged in the actual blocking positionindependently of the actual relative rotary position of the sole holderwith respect to the return cam is constantly in engagement with thisface, which ensures the blocking effect. Consequently, theunidirectional blocking arrangement blocks practically immediately inany relative rotary position of the sole holder as soon as the latter isurged in the opening direction.

Hence, the sole holder may not be fully downwardly engaged, for exampledue to the presence of ice on the surface of the ski or of the sole, orbecause of an over-standard sole thickness, but the heel unit is capableof perfect operation, i.e. the desired return and holding function aswell as case the possibility of a safety release are ensured.

In a respective pivoting of the sole holder in the closing direction,the blocking member slides without force transmission along the circularor semicircular-shaped bearing face, such that the sole holder can bebrought into the closing position with a reduced effort when theblocking arrangement is released. Thus, during this closing movement itis not necessary to overcome the relatively high spring force exerted bythe spring arrangement. Finally, the arbitrary or manual releaserequires a reduced effort while avoiding the action of the springarrangement. For this purpose, it is only necessary to release theblocking member against a low spring force.

Thus, the basic idea of the invention is to design features such thatthe sole holder can practically freely rotate in the closing directionwith respect to the return cam urged by the spring arrangement. In theevent of a bias in the opening direction, however, the sole holder iscoupled to the spring urged return cam which ensures the return and asafety release immediately and substantially independently of the actualrelative rotary position. Owing to this, it is also ensured that theunidirectional blocking arrangement can be released against a low springforce. The arbitrary opening of the heel unit is thus possible only bymeans of a reduced effort while avoiding the action of the springarrangement. Finally, the entire stroke of the spring arrangement isalways available in the event of a safety release, substantiallyindependently of the actual relative rotary position of the sole holderwith respect to the return cam. The desired release characteristic isthereby also maintained, even when the sole holder cannot be fullydepressed into its predetermined closing position, for example due tothe formation of ice. If the sole holder is prevented from pivoting intoits final closing position, for example due to the presence of ice orsnow between the ski boot and the ski, and the snow or ice melts duringuse, the unidirectional blocking arrangement which acts as afree-running drive allows the sole holder to be automatically adjustedin the direction of the predetermined final rotary position due to thepressure of the ski boot without disadjustment of the cam and thus ofthe release characteristic.

In accordance with another embodiment, the unidirectional blockingarrangement is realized as a friction-type unidirectional blockingarrangement.

In this case, the frictionally-blocking unidirectional blockingarrangement can comprise at least one blocking pawl pivotally mounted onthe sole holder and the bearing face is a substantially smooth bearingface provided on the return cam. Alternatively, thefrictionally-blocking unidirectional blocking arrangement can berealized in the form of a roller-type unidirectional blockingarrangement which has at least one blocking roller or ball.

When a friction-blocking arrangement comprises a pawl, the blocking pawlis preferably pivotally mounted on the sole holder, and the bearing andsliding face which serves as counter-surface is substantially smooth andprovided on the return cam. However, it is also possible to design theheel unit in such a manner that the pivotable blocking pawl is mountedon the return cam and the substantially smooth bearing face which formsthe counter-surface is provided on the sole holder. In this case,however, the unidirectional blocking arrangement blocks when the heelunit is biased in the opening direction and allows a free pivoting ofthe sole holder in the closing direction, in the manner of afree-running drive.

In a further variant, the blocking roller is permanently resilientlyurged in an intermediate space which tapers in a wedge-like manner andis guided on a circular track concentric to the axis of the cam and ofthe sole holder. Therefore, it is ensured that this blocking member isalso always maintained in contact with the circular or semicircularbearing face which is also concentric to this axis.

By way of example, the blocking rollers can be made of ceramic materialor of steel. In the case of ceramic rollers, only one blocking rollerwill be generally sufficient, whereas in the case of steel rollers,provision will preferably be made for two blocking rollers opposite toeach other or arranged symmetrically. Thereby, one takes into accountthat ceramic rollers are significantly harder and more resistant thansteel rollers, and that it is thus appropriate to distribute thepressure over a higher number of symmetrically arranged rollers, inparticular in the case of steel rollers.

In a further variant, the unidirectional blocking arrangement comprisesat least one blocking roller and a roller cage rotatably mounted aboutthe axis of the cam and of the sole holder, the roller cage being fixedto the sole holder for rotation therewith. Further, an intermediatespace which tapers on one side in a wedge-like manner is formed betweenthe bearing face and a counter-surface provided on the roller cage, andthe blocking roller which is guided on a circular track concentric tothe axis of the cam and of the sole holder is resilient urgend into theblocking position. forms a kind of free-running drive arrangementbetween the sole holder and the return cam, which blocks immediately ifthe sole holder is urged in the opening direction, independently of theactual rotary position of the sole holder, whereas the latter isreleased in the event of a predetermined bias in the closing direction,applied for example by the ski boot or resulting from a voluntaryrelease of the heel unit. It is important that the roller cage is alwaysrotated together with the sole holder about the axis of the cam and ofthe sole holder, and that the blocking roller can be displaced withrespect to the roller cage, for example for a voluntary release andpreferably against a light spring force.

A pawl-type unidirectional blocking arrangement can be used in which theblocking pawl has a tooth and the bearing face of the return camcomprises a toothed sector. As compared to a continuous adjustment andan effectively play-free holding of the ski boot provided by theprevious embodiments, a slight play can be observed in this alternative,which corresponds to the pitch of the teeth of the toothed sector, butwhich is not disadvantageous for most practical applications.

If a manual actuation lever is pivotally mounted on the base body,preferably about the axis of the return can and of the sole holder, thesole holder can be rotated without problem in the opening directionafter the unidirectional blocking arrangement has been released. Inprinciple, that the manual actuation lever can also drive the soleholder in the closing direction, and the sole holder is released becausethe friction-type unidirectional blocking arrangement acts as afree-running drive. In a further variant, the release means provided forthe release of the friction-type unidirectional blocking arrangement canbe manually actuatable independently of the actuation lever coupled tothe sole holder. Thus, the actuation lever can be actuated in theopening direction either in a usual manner against the spring forceexerted by the spring arrangement, or by avoiding this spring force whenthe friction-type unidirectional blocking arrangement is released. Apush-button mechanism, an electrically controlled mechanism or the likecan be provided to release the friction-type unidirectional blockingarrangement.

Further, the drive of the sole holder by the manual actuation lever canoccur in a delayed manner in such a way that at the beginning of theactuation of the lever and before the sole holder is driven, thefriction-type unidirectional blocking arrangement is firstly released.In this case it is also possible to allow the release of thefriction-type unidirectional blocking arrangement for the opening of theheel unit.

In a further variant with a view to ensuring, on releasing theunidirectional blocking arrangement coupled to the manual actuationlever, that the blocking arrangement also blocks when the lever is notactuated, the manual actuation lever an the sole holder are expedientlyconstantly biased in a starting rotary position in which thefriction-type unidirectional blocking arrangement is not yet released.

As an alternative provision can be made for a delayed drive of the soleholder in the opening direction by means of the manual actuation lever.In such an event, the sole holder can also be rotated in the closingdirection by means of the manual actuation lever. On driving the soleholder in the opening direction and in the closing direction, thedriving member engages thus respectively one of the two opposed limitsof the opening through which extends the driving member.

Especially when using a pawl-type blocking arrangement, the respectivedriving member provided on the manual actuation lever can be used bothfor driving the sole holder and for releasing the friction-type blockingarrangement.

When using a roller-type unidirectional blocking arrangement, theblocking roller can be advantageously connected to the manual actuationlever and be resiliently maintained by the latter in the actual blockingposition. Since the blocking roller is fixed on the manual actuationlever and the latter is able to rotate about the axis of the cam and ofthe sole holder, it is simultaneously ensured that the blocking rolleris guided on a circular track concentric to the bearing and slidingsurface and is thus permanently in contact with the counter-surface, orremains at the shortest possible distance from the latter. Here again,an immediate blocking is possible at any time, independently of theactual relative rotary position of the sole holder.

The sole holder can be slightly biased in the opening direction, wherebythe sole holder is automatically rotated into the opening position assoon as the friction-type unidirectional blocking arrangement isreleased. For this purpose, one can for example, provide a springbetween the sole holder and the base body.

In a further embodiment, provision is made for a release arrangementassociated to the unidirectional blocking arrangement and activated as afunction of the rotary position of the sole holder, said unidirectionalblocking arrangement being released in a forced manner by this releasearrangement when the sole holder reaches a rotary position within arotation range limited on the one hand by a release position for the skiboot and on the other hand by the opening position. With thisarrangement, it can also be ensured that the sole holder isautomatically decoupled from the return cam as soon as the sole holderhas reached a rotary position such that the ski boot is released,especially during a forward fall in the forward direction. Thus, thereturn cam can return to its starting rotary position, without drivingthe sole holder, which facilitates the new introduction into the heelunit.

When the control surface of the spring-urged return cam is realizedwithout a culminating point, the closing of the heel unit can alsoalways occur under a reduced effort by avoiding the relatively highspring force exerted by the spring arrangement. After the ski boot hasbeen released following a safety release, the return cam is immediatelyreturned by the spring arrangement, and the sole holder is returned bymeans of the return cam. For an arbitrary or manual release it is thennecessary to release the unidirectional blocking arrangement acting as afree-running drive, which can be done with a greatly reduced effort. Forthis purpose, it is sufficient to overcome the light spring force whichurges the blocking member. Thereafter, the sole holder can be upwardlypivoted without effort. Also during the closing of the sole holder, aninfluence of the cam and of the spring arrangement which urges thelatter is excluded due to the free-running drive between the sole holderand the cam under the form of the unidirectional blocking arrangement.

In a further variant, the sole holder can be urged in the openingdirection by means of a tilting mechanism or the like, whereby the soleholder is automatically brought into its final opening position, afterrelease of the unidirectional blocking arrangement, and is maintained inthis position, for example, by means of a light spring force.

As long as the sole holder occupies a rotary position between itsclosing position and a predetermined intermediate position, the soleholder can also be urged toward the closing position, preferably bymeans of the same tilting mechanism, which results in an automaticpost-adjustment of the heel unit, especially in the event a layer of iceor snow present between the ski boot and the ski becomes thinner, forexample under the pressure from vibrations and shocks.

BRIEF DESCRIPTION OF THE DRAWINGS

These drawings show:

FIG. 1 is a schematic cross-sectional view of a safety heel unitcomprising a friction-type unidirectional blocking arrangement under theform of a pawl-type blocking arrangement, in the closing position,

FIG. 2 shows the heel unit shown in FIG. 1 when the sole holder is urgedby the ski boot in the opening direction,

FIG. 3 shows the heel unit shown in FIG. 1, just before a voluntaryrelease by means of the manual actuation lever, the sole holder stilloccupying its closing position,

FIG. 4 shows the heel unit of FIG. 1 after manual release, the soleholder being rotated into the opening position,

FIG. 5 shows a top view in horizontal cross-section of the heel unit ofFIG. 1.

FIG. 6 shows a portion of an other embodiment of the heel unitcomprising a roller-type unidirectional blocking arrangement, showingthe blocking arrangement,

FIG. 7 is a schematic cross-sectional view of a further variant of asafety heel unit equipped with a roller-type unidirectional blockingarrangement, in the closing position,

FIG. 8 shows the heel unit of FIG. 7, in which the sole holder is urgedby the ski boot in the opening direction,

FIG. 9 shows the heel unit of FIG. 7, after release, with the soleholder pivoted into the opening position,

FIG. 10 shows the heel unit of FIG. 7, just before voluntary manualrelease by means of the release lever, in which the sole holder stilloccupies its closing position,

FIG. 11 shows a portion of the roller-type unidirectional blockingarrangement of the heel unit of FIG. 7,

FIG. 12 shows a schematic representation of the additional tiltingmechanism included in the heel unit of FIG. 7,

FIG. 13 shows a schematic cross-sectional view similar to that of FIG. 7of a further variant of a safety heel unit equipped with a pawl-typeunidirectional blocking arrangement, in the closing position, and

FIG. 14 shows a detail of a variant of the embodiment of FIG. 13.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 5 show a heel unit 10 of a safety ski binding, whichcomprises a base body 14 suitable to be fixed to the ski 12 and on whicha heel unit 16 is pivotally mounted about a transverse axis A, the soleholder being engaged by the sole 18 of the ski boot 20 (see FIG. 2). Forthis purpose, the sole holder 16 is provided with a down-holding bracket22 and a rest lug 24 for the sole.

A return cam 26 is pivotally mounted about the same axis A on the basebody 14. The cam is urged into the starting position illustrated inFIGS. 1 and 3 to 5 by a spring arrangement 28 comprising a compressionspring 30.

The spring 30 is braced on a first spring abutment 32 at the end remotefrom the return cam 26, the abutment being a cup-shaped adjustment screwprovided with an outer thread 34 which cooperates with an inner thread36 of a cylindrical bore 38 in the base body 14 (see FIGS. 1 and 2).

The opposed end of the compression spring 30, adjacent to the return cam26 engages a second spring abutment 40 which also has the shape of a cupand is guided in the cylindrical bore 38 in the manner of a piston.

The return cam 26 has a semicircular portion 44 provided with a flatcontrol surface portion 46, against which the second spring abutment 40rests in a flat manner via its front face 42 (see FIGS. 1 to 3) when thereturn cam 26 is not urged by the sole holder 16 (see especially FIGS. 1and 3 to 5).

As best seen in FIG. 5, the axis A of the cam and of the sole holder isaccommodated in two side walls 48, 50 of the base body 14, spaced fromeach other. The sole holder 16 pivotally mounted about the same axis Aon the base body 14 has a U-shape in longitudinal cross-section, the twoarms 52, 54 thereof being located inwardly of the two side walls 48, 50of the base body 14 which are parallel to these arms. The arms arepivotally mounted on the end regions of the return cam 26. The returncam 26 is cylindrical, with the exception of the semicylindrical portion44.

In a corresponding manner, a manual actuation lever 64 serving to themanual release of the heel unit 10, which has also a U-shape inlongitudinal cross-section, is pivotally mounted via its two arms 56, 58located between the lateral walls 48, 50 and the arms 52, 54 on the endregions of the cylindrical return cam 26. Accordingly, the manualactuation lever also rotates about the common axis A (see in particularFIG. 5).

A friction-type unidirectional blocking arrangement, realized as apawl-type blocking arrangement 60' and comprising at least one blockingpawl 62' as blocking member, is mounted between the sole holder 16 andthe return cam 26 so as to rotate about the same axis A (FIGS. 1 to 5).This pawl-type blocking arrangement 60' is realized in such a mannerthat it blocks when the sole holder 16 is urged in the openingdirection, and in the present embodiment it can be released by means ofthe manual actuation lever 64 against a low spring force exerted by aspring member 66.

In the embodiment shown in FIGS. 1 to 5, the blocking pawl 62' ispivotally mounted on the sole holder 16. Spring 66 urges it against asubstantially smooth bearing face 68 of the return cam 26. This bearingface 68, which acts as a counter-surface for the blocking pawl 62' whichis permanently resiliently urged in the actual blocking position betweenthe return cam 26 and the sole holder 16, has a circular or semicircularshape and is concentric to the axis A of the cam and the sole holder.

The blocking pawl 62' frictionally engages in a force-locked manner thiscircular or semicircular counter-surface 68 concentric to the axis A ofthe cam and of the sole holder when the sole holder 16 is biased in theopening direction. It is permanently in sliding contact on this surface68 when the sole holder 16 is biased in the closing direction,substantially independently of the actual relative rotary position ofthe sole holder 16 with respect to the return cam 26.

Since the control surface 46 of the return cam 26 urged by the springarrangement 28 has no culminating point (see for example FIGS. 1 and 2),the return cam 26 is always urged by the spring arrangement 28independently of the actual rotary position of the cam 26 and only inthe closing direction (see for example FIG. 1).

The manual actuation lever 64 serves both to drive the sole holder 16towards the opening or closing position and to release the friction-typeunidirectional blocking arrangement realized as a pawl-type blockingarrangement 60'.

For this purpose, a drive member 76 is provided on the manual actuationlever 64. This drive member 76, in the form of a cylindrical stem andrigidly connected to the lever, is mounted on the two arms 56, 58 of themanual actuation lever and extends through mutually aligned openings 78of the arms 52, 54 of the sole holder 16 (see for example FIG. 5).

The opening cross-section of the openings 78 provided in the sole holder16 is larger than the cross-section of the cylindrical drive member 76which extends through these openings 78.

Since the cylindrical drive stem 76 is fixed on the manual actuationlever 64, the blocking pawl 62' of the friction-type unidirectionalblocking arrangement, in the form of a pawl-type blocking arrangement,is additionally released by a corresponding bias. For this purpose, whenthe manual actuation lever 64 rotates in the opening direction by meansof the drive member 76, the blocking pawl 62' covers the two openings 78as far as, 62' is firstly lifted from the bearing surface 68 of thereturn cam 26 and the sole holder 16 is thereafter driven in the openingdirection with a corresponding delay (see for example FIGS. 3 and 4).

The opening section of the openings 78 must therefore be sized in such amanner that when the lever 64 is actuated in the opening direction bythe drive member 76, the blocking pawl 62' can be released first and thesole holder 16 can then be driven following a corresponding delay.

The manual actuation lever 64 and the sole holder 16 are additionallycoupled by means of a spring member 74 and urged by the latter towards astarting relative position, in which the pawl-type blocking arrangement60' is not yet released (see for example FIG. 1).

While in the described embodiment the release of the unidirectionalblocking arrangement takes place by means of the manual actuation lever64, it is possible to include release means by means of which theunidirectional blocking arrangement can be released independently of themanual actuation lever, optionally coupled to the sole holder 16. Forthis a push-button mechanism, an electronically controlled mechanism, orthe like can be provided.

In the present case the heel unit is manually opened by actuation of thelever 64 after the unidirectional blocking arrangement has beenreleased. However, the sole holder 16 can also be gently urged in theopening direction, such that the latter is automatically tilted in itsopening position after release of the unidirectional blockingarrangement, eventually driven by the manual actuation lever 64.

FIG. 6 shows a portion of a further variant of the heel unit showing thefriction-type unidirectional blocking arrangement. It differs from theembodiment of FIGS. 1 to 5 only in that the friction-type unidirectionalblocking arrangement is a roller-type unidirectional blockingarrangement 60" instead of the pawl-type blocking arrangement. It has atleast one blocking roller 62".

In this case too, the circular or semicircular-shaped bearing surface 68is substantially smooth and provided for example on the return cam 26.

To form an intermediate space 72 which tapers on one side in awedge-like manner, the counter-surface 70 concentric to the return cam26 and provided on the sole holder 16 is a plane inclined with respectto the tangent T of the bearing surface 68 passing through the contactpoint B with the blocking roller 62". To form the intermediate space 72which tapers on one side in a wedge-like manner, this counter-surface 70can also in principle be eccentrically curved.

The blocking roller 62" is connected to the manual actuation lever 64(see also FIGS. 1 to 3) which is pivotable about the axis A of the camand of the sole holder and is coupled to the sole holder 16 via thespring member 74.

Thus, the blocking roller 62" which is constantly elastically urged intothe intermediate space 72, is guided on a circular track K, concentricto the axis A of the cam and the sole holder. The blocking roller 62" istherefore always in contact with the circular or semicircular-shapedbearing surface 68 concentric to the axis A.

By way of example, the blocking roller 62" can be made of ceramicmaterial, or it can be covered with ceramic material, or it can be madeof steel.

In the case of a blocking roller 62" made of ceramic material, oneroller is generally sufficient. If the rollers are made of steel,provision is made for at least two blocking rollers 62" opposite fromeach other or arranged symmetrically. The pressure will then bedistributed over a larger number of symmetrically arranged rollers.

Since these rollers exhibit, according to the selected material,different hardnesses and resistances as well as different frictioncoefficients, the cone angles φ must also be differently selected.

In FIG. 6, the counter-surface 70 of the sole holder 16 is shown insolid lines for blocking rollers made in ceramic material, and thecounter-surface 70' is shown in dashed lines for rollers made of steel.

The cone angle is defined as the angle φ between the normal N to thebearing and sliding surface 68 at the contact point B with the blockingroller 62" and the connection line V between the two contact points B, Cof the blocking roller 62" with the bearing and sliding surface 68 andwith the counter-surface 70 or 70'. In the case of a blocking roller 62"of ceramic material, the tangent of this angle α is equal to about 0.3in the present embodiment, and to about 0.1 in the case of steelrollers.

The heel unit of the invention operates in the following manner:

In the embodiment illustrated in FIGS. 1 to 5, not only the sole holder16 is driven by the drive member 76 in the opening or closing direction,but the unidirectional blocking arrangement 60 is also released. In theembodiment of FIG. 6, when the lever is actuated in the openingdirection, the release of the friction-type unidirectional blockingarrangement 60" takes place as the blocking roller 62" connected to thislever is moved in the other direction out of the intermediate space 72which tapers in a wedge-like manner. For the rest, the two variantsoperate in a similar manner.

In the view of FIG. 1, neither the sole holder 16 nor the manualactuation lever 64 are biased. Therefore, the sole holder 16 occupiesits closing position, whereas the return cam 26 urged by the springarrangement 28 is held in its starting rotary position corresponding tothe closing position.

The sole holder 16, as well as the manual actuation lever 64, are heldby the spring 74 in their starting relative rotary position in which thedriving member 76 contacts the edge of the opening 78 remote from theblocking member 62' and is thus disengaged from the blocking member 62'.

In FIG. 2, the sole holder 16 is urged by the ski boot 20 in the openingdirection and tilted upwardly away from the final position. The manualactuation lever 64 is then driven by the sole holder 16. Owing to thespring 74, the driving member 76 remains in contact with the edge of theopenings 78 of the sole holder 16 remote from the blocking member 62'.As a result, the friction-type unidirectional blocking arrangement 60'is blocked, whereby the return cam 26 is also rotated in the openingdirection about the common axis A together with the sole holder 16against the relatively high spring force exerted by the compressionspring 30 of the spring arrangement 28.

Since the opening force exerted by the ski boot 20 on the sole holder 16decreases, the sole holder 16 is again urged downwardly into the finalclosing position by the compression spring 30, with the return cam 26and the friction-type unidirectional blocking arrangement 60' stillbeing in a blocking condition.

If the force exerted by the ski boot 20 on the sole holder 16 in theopening direction overcomes the return force, the boot is releasedupwardly out of the sole holder 16. Immediately after such a release,the sole holder is pivoted back to the closing position due to thereturn force (see FIG. 1).

In FIG. 3, the heel unit is shown in a position immediately before avoluntary release by means of the manual actuation lever 64. This manualactuation lever 64 is then already tilted or pushed downwardly in thedirection of the arrow, as far as the blocking pawl 62' is lifted fromthe bearing surface 68 by means of the driving member 76, and thefriction-type unidirectional blocking arrangement 60 realized as apawl-type blocking arrangement is thus released.

As soon as the manual actuation lever 64 is further pushed downwardly,the sole holder 16 is driven in the opening direction, by the samedriving member 76. The return cam 26 remains then in its starting rotaryposition because the friction-type unidirectional blocking arrangement62' is released, such that one can open the heel unit with a minimumeffort while avoiding the return force exerted by the spring arrangement28.

In FIG. 4, the manual actuation lever 64 is fully displaced downwardlyin its opening position in which it extends generally parallel to theski 12. When the return cam 26 thereafter takes its starting rotaryposition, the sole holder 16 driven by the lever has reached its openingposition.

The heel unit is thereafter closed by pivoting the sole holder 16 againdownwardly in the closing direction, for example by means of the skiboot and/or the lever. During this rotary movement, the blocking member62' of the friction-type unidirectional blocking arrangement 60' whichoperates in the manner of a free-running drive slides along the circularor semicircular-shaped bearing surface concentric to the axis A. Duringthis closing movement of the sole holder, the manual actuation lever 64also coupled to the sole holder via the spring 74 is driven, providedthis lever is simultaneously actuated.

As soon as the sole holder is again urged in the opening direction, thefriction-type unidirectional blocking arrangement 60', is automaticallyblocked to again establish a rigid coupling between the sole holder 16and the return cam 26 urged by the spring. The behaviors described inconnection with FIG. 2 again take place.

It is important that owing to the permanent contact if the blockingmember 62' against the circular or semicircular-shaped counter-surface68 concentric to the axis A, or the positioning of these two componentsat as small a distance as possible, the friction-type unidirectionalblocking arrangement is able to block at any time, i.e. independently ofthe actual relative rotary position of the sole holder 16, as soon asthe sole holder is correspondingly urged in the opening direction. Thus,blocking is possible even if the sole holder 16 cannot be fully pivoteddownwardly into its final closing position, for example because ice orsnow is trapped between the shoe sole and the surface of the ski.

Independently of the actual starting rotary position of the sole holder,on occurrence of any bias in the opening direction, the return cam 26 isalso always tilted against the spring force of the compression spring 30from the final position shown for example in FIG. 1, such that theentire stroke of the spring is always available for a safety release.

As a variant of the described embodiments, release means for releasingthe friction-type unidirectional blocking arrangement, which can beactuated independently of a manual actuation lever, or the like, canoptionally be provided and coupled to the sole holder. For this purpose,a push-button mechanism, an electronically controlled mechanism and/orthe like can be used. Features can be included for automatically tiltingthe sole holder in the opening direction after a release of theunidirectional blocking arrangement, for example in the form of a springarranged between the base body and the sole holder.

FIG. 7 to 12 show a further embodiment of a heel unit 10 comprising afriction-type unidirectional blocking arrangement realized as aroller-type unidirectional blocking arrangement 60" which also comprisesa base body 14 intended to be secured to the ski. A sole holder 16 ispivotally mounted on the base body about an axis A and engages the soleof a ski boot with a down-holding jaw 22 and a bearing lug 24.

A return cam 26 pivotally mounted on the base body 14 about the sameaxis A is urged by a spring arrangement 28 into the starting positionshown in FIGS. 7, 9 and 10. The spring arrangement 28 comprises acompression spring 30, which is supported on a first spring abutment 32at the end remote from the return cam 26. The spring abutment isrealized as a cup-shaped adjustment screw provided with an outer thread34 which cooperates with an inner thread 36 of a cylindrical bore 38 inthe base body 14 (see especially FIG. 7). At the other end adjacent tothe return cam 26, the compression spring 30 is supported against asecond spring abutment 40, also having the shape of a cup, which isguided in the cylindrical bore 38 in the manner of a piston.

The return cam 26 comprises a partly cylindrical portion 44, concentricto the axis A of the cam and of the sole holder, on which are definedtwo projections 82, 84 spaced from each other. The second springabutment engages these projections when the return cam 26 is not loadedby the sole holder 16 (see in particular FIGS. 7, 9 and 10). The springabutment is engaged via its end face 42 which is corresponding curved.Thus, the second spring abutment 40 contacts at two places S1 and S2 thereturn cam 26 which occupies its starting position. As soon as thereturn cam 26 is rotated out of its starting position by the sole holder16 and the roller-type unidirectional blocking arrangement 60"againstthe spring force exerted by the compression spring 30, the return cam 26contacts the end face 42 of the second spring abutment 40 only with thecurved control surface portion 46 on the upper projection 82 (see FIG.8).

The roller-type unidirectional blocking arrangement 60" between the soleholder 16 and the return cam 26 comprises a roller cage 80 rotatablymounted about the axis A of the cam and of the sole holder, and twoblocking rollers 62" arranged diametrically opposite to each other,which are each received in an intermediate space 72 located between thebearing and sliding surface 68 of the return cam 26 and acounter-surface 70" of the roller cage 80. The substantially smoothbearing surface 68 provided at the exterior on the return cam 26 has acircular or semicircular outline concentric to the axis of the cam andof the sole holder. The counter-surfaces 70" provided at the interiorinside the roller cage 80 are each formed so that the respectiveintermediate space 72 tapers in a wedge-like manner in one of therotation directions (in the present case in the counter-clockwisedirection). The counter-surface 70" are preferably oriented in such amanner that an angle α of about 10° C. is formed between the normal N ofthe bearing surface 68 at the contact point B with the blocking roller62" and the normal N' of the counter-surface 70" at the contact point Cwith the blocking roller 62" (see FIGS. 11 and 7).

The roller cage 80, which in the present embodiment is distinct from thesole holder 16, is brought into its rotary position with respect to thesole holder 16 by means of two abutment faces 91, 100 spaced from eachother and provided on the sole holder 16. Due to the engagement of theroller cage 80 by the counter-surface 98 or 100, a fixed coupling isestablished between the roller cage 80 and the sole holder 16 for jointrotation. Appropriately, a slight play can be left here between theroller cage 80 and the sole holder 16, as is indicated in FIG. 7 by asmall intermediate space ZW, between the lower abutment face 100 and theroller cage 80 when the roller cage 80 simultaneously directly contactsthe upper abutment face 98.

As is best seen in FIG. 11, the blocking rollers 62" which areresiliently urged in the blocking position are guided on a circulartrack K having a radius R1, concentric to the axis A of the cam and thesole holder. The radius of the circular track is at least substantiallylarger, by the radius r of the two cylindrical blocking rollers 62",than the radius R2 of the bearing surface 68 on the exterior of thepartly cylindrical portion 44 of the return cam 26.

The blocking rollers 62" are mounted on a release lever 64" which ispivotally mounted on the base body 14 about the axis A of the cam andthe sole holder. This release lever 64" is urged by means of a springmember 74" in a starting rotary with respect to the roller cage 80,position in which the blocking rollers 62" occupy their blockingposition shown in FIGS. 7, 8 and 11.

The spring member 74", which is for example a spring made ofpolyurethane, a compression spring or a metal leaf spring, is arrangedbetween a spring abutment 116 on the release lever 64" and the rollercage 80.

The release lever 64 is bent and mounted at the interior of the soleholder 16 which is extended by a lever arm 120. This release lever isaccessible from the outside for a manual actuation at the upper or rearhead 122. The release lever 64 can be pivoted rearwardly against therelatively low spring force 74" and into the interior of the sole holder16 relative to the roller cage 80 as far as the blocking rollers 62" arebrought into the release position shown in FIGS. 9 and 10, where theblocking rollers 62" are located in the respective intermediate spaces72 with a certain play Sp1.

It is possible to add to the unidirectional blocking arrangement 60,realized in the present embodiment as a roller-type unidirectionalblocking arrangement 60", a release device actuated independence on therotary position of the sole holder 16. The release device comprises arelease piston 86, guided in a bore 92 of the sole holder 16, andcooperating with a climbing ramp 102 provided on the base body 14 andwith a surface portion 104 of the base body 14 which follows theclimbing ramp. The release piston urges the release lever in the openingdirection and has a partly cylindrical shape concentric to the axis A ofthe cam and of the sole holder.

On the climbing ramp 102 and at the remote end of the cylindricalsurface portion 104, the release piston 86 includes an abutment 88 whichis held against an abutment surface 80 of the sole holder 26 when therelease lever 64" is not actuated. On its side remote from the abutmentsurface 90, the abutment 88 has an inclined surface 94 which is engagedby the rear end 122 of the release lever 64" via a slightly curvedcounter-surface 96, the release lever being urged by a spring.

The release piston 86 and the climbing ramp 102 as well as the partlycylindrical surface portion 104 are arranged with respect to each otherand designed in such a manner that the unidirectional blockingarrangement, realized for example as a roller-type unidirectionalblocking arrangement 60", is also always compulsorily released when thesole holder 16 reaches a rotary position within a rotary range definedat least substantially by a release position of the ski boot (see FIG.8) and the opening position (see FIG. 9).

Between the base body 14 and the roller cage 80, which is solidlycoupled to the sole holder 16, is a tilting mechanism 106. It comprisesa cylindrical spring housing 108 pivotally mounted about an axis H on aconnection arm 114 of the roller cage 80, a stem-shaped spring abutment110 pivotally mounted about an axis G on the base body 14 at one end andguided in the spring housing 108, and a compression spring 112 arrangedbetween the spring housing 108 and the spring abutment 110. The twopivot axes G, H extend parallel to the axis A of the cam and of the soleholder and parallel to the blocking rollers 62". At one end, thecompression spring 112 rests against the bottom of the spring housing108 which is open on one side for receiving the stem-shaped springabutment 110. At the other end, the compression spring 112 can rest forexample against the pivot axis G (see FIG. 9) or against a piston 118guided in the cylindrical spring housing 108 and provided on the springabutment 110 (see FIG. 12).

In the first case, the spring housing 108 can be provided with lateralslots 124 such that it can be displaced against the force of the springpartly up to beyond the pivot axis G. In this case, the stem-shapedspring abutment 110 is at least partly surrounded by the compressionspring 112.

In the closing position of the sole holder 16, the tilting mechanism 106occupies the tilting position designated P1 in FIG. 12, in which theroller cage 80 and consequently the sole holder 16 are urged by a slightspring force F into the closing position. If the sole holder I6 isrotated away from the closing position, the spring 112 is progressivelycompressed until it reaches an intermediate rotary position P0. Afterhaving reached this intermediate rotary position PO, the tiltingmechanism 106 acts in the opening direction, until it has reached therotary position P2 corresponding to the opening position of the soleholder 16, in which the roller cage 80, and via the latter the soleholder 16, is urged in the opening direction by a slight spring forceF'. In this case, the pivot axis H is guided along a circular path KBconcentric to the axis A of the cam and the sole holder.

Consequently, the sole holder 16 is urged in the opening direction bythe tilting mechanism 106, as long as it occupies a rotary positionbetween a opening position and a predetermined intermediate position,and it is urged in the closing direction by the same tilting mechanismas long as it occupies a rotary position between its closing positionand the predetermined intermediate position.

The variant shown in FIGS. 7 to 12 of the heel unit of the inventionoperates in the following manner:

In the view of FIG. 7, neither the sole holder 16 nor the release lever64" are urged. Therefore, the sole holder 16 occupies its closingposition in which it is additionally urged by the tilting mechanism 106.

The blocking rollers 62" are held in their blocking position by therelease lever 64" which is resiliently loaded, such that the roller-typeunidirectional blocking arrangement 62" ensures a solid coupling betweenthe sole holder 16 and the spring-loaded return cam 26 as soon as thesole holder 16 is urged in the opening direction by the ski boot.

In accordance with FIG. 8, the sole holder 16 is urged in the openingdirection by the ski boot (shown only in FIG. 2) and rotates upwardlyaway from the closing position. Until reaching the rotary position WFillustrated in FIG. 8, in which the release piston 86 comes inengagement on the climbing ramp 102, the roller-type unidirectionalblocking arrangement 60" remains blocked. Thus, the return cam 26 isalso rotated together with the sole holder 16 in the opening directionabout the common axis and against the relatively high spring forceexerted by the compression spring 30 of the spring arrangement 28.

As indicated in FIG. 11, the roller cage 80 is thus driven by the soleholder in the direction of the arrow I, while the blocking rollers 62",which are mounted with a certain play Sp2 in the release lever 64", arepushed in the opposite direction J by the resiliently-loaded releaselever 64", such that these rollers take their blocking position. As aresult, the spring-loaded return cam 26 is displaced in the direction ofthe arrow L.

If the force exerted by the ski boot on the sole holder 16 in theopening direction overcomes the return force, the boot is releasedupwardly out of the sole holder 16. In the corresponding rotary positionof the sole holder 16 beyond the rotation region WS under resilientload, the release piston 86 is already engaged against the partlycylindrical surface portion 104 of the base body 14, whereby the releaselever 64" is forcibly rotated with respect to the roller cage 80 as faras the blocking rollers 62" take their release position. The return cam26 is consequently returned to its starting rotary position withoutdriving the sole holder 16. In contrast, the latter is brought by thetilting mechanism 106 into the opening position shown in FIG. 9.

In FIG. 10, the heel unit is shown in a position immediately before avoluntary manual release. While the sole holder 16 still occupies itsclosing position, the release lever 64" is manually pivoted against thespring force 74", for example by means of a ski pole, as far as theblocking rollers 62" take their release position inside the intermediatespaces 72, and the roller-type unidirectional blocking arrangement 60"is consequently released.

If the release lever 64" is further actuated, the sole holder 16 can bepivoted in the opening direction, for example by means of its lever arm120, without the spring-loaded return cam 26 being then driven. Thelatter remains in its starting position shown in FIG. 10.

To close the heel unit, the sole holder 16 is rotated downwardly in theclosing direction, for example by means of the ski boot and/or by meansof its lever arm 120. During this rotary movement the blocking rollers62" of the unidirectional blocking arrangement 60", which operates as afree-running drive mechanism, are guided freely along the circular orsemicircular bearing surface 68 concentric to the axis A. After thetilting mechanism 106 has reached the intermediate rotary position P0(see FIG. 11) the closing movement is furthermore assisted by tiltingmechanism 106, by means of which the sole holder 16 is then urged in theclosing direction via the roller cage 80. Thus , there occurs anautomatic post-adjustment of the heel unit, for example, in those casesin which a layer of ice and/or snow present between the shoe sole andthe surface of the ski progressively disappears, especially under theforces generated by shocks and vibrations and under the pressure exertedby the shoe. Simultaneously, an automatic adaption to different solethicknesses is reached.

As soon as the sole holder 16 is again urged in the opening direction,the roller-type unidirectional blocking arrangement is automaticallyblocked, which establishes again a solid coupling of the sole holderwith the return cam 26.

The embodiment shown in FIG. 13 comprises a unidirectional blockingarrangement, designated by the reference 160, including a toothed pawl.Besides, this embodiment includes a certain number of components whichhave already been described in connection with the embodiment of FIGS. 7to 12, which will not be described again in detail. In FIG. 13, theybear the same reference numerals.

Here, the pawl 162 is rotatably mounted on an intermediate cage 163which is in turn rotatably mounted about the common axis A of the returncam 26 and of the sole holder 16. The cage 163 abuts against the soleholder 16 both directly via a first bearing surface 165 and indirectlyvia a second bearing surface 169 through a resilient member 167. Thepurpose of the resilient member 167 is merely to compensate formanufacturing tolerances of the sole holder 16 and of the cage 163, suchthat the latter is practically fixedly connected to the sole holder 16.It is even possible to omit such an intermediate cage and to mount therotary pawl 162 directly on the sole holder 16.

On one side of its rotation axis, the pawl 162 ends in a tooth 171radially directed toward the axis A, and the bearing surface 68 of thereturn cam 26 comprises a toothed sector 173. A spring 175 engages theintermediate cage 163 and biases the pawl 162 in such a manner that itstooth 171 engages this toothed sector.

On its side opposite from the rotation axis, the pawl comprises arelease arm 177 inclined with respect to a radial direction from thecommon axis A of the return cam 26 and the sole holder 16.

In the position shown in FIG. 13, the engagement of the tooth 171 of thepawl 162 in the toothed sector 173 of the return cam 26 causes aforce-locked cooperation between the sole holder 16 and the return cam26 in the opening direction of the heel unit 10, and contrarily apractically effortless rotation of the sole holder 16 with respect tothe return cam 26 in the closing direction of the heel unit 10,practically in the same manner as in the previous embodiments, the onlydifference being that the blocking occurs here only for a determinednumber of relative positions for which the tooth 171 of the pawl 162engages between the teeth of the toothed sector 173 of the return cam.Nevertheless, the pitch of the teeth of the toothed sector can beselected sufficiently small to obtain a blocking action practicallyindependently of the relative rotary position of the sole holder and thereturn cam.

In this embodiment, the manual actuation lever 64 is rotatably mountedabout an axis 179 which extends through the extension arm 120 of thesole holder 16, and ends in a finger 181 generally directed toward theaxis A and located at a distance from the latter which is at most equalto the radial distance between the axis A and the release arm of thepawl 162. A spring 183 arranged between the sole holder 16 and theactuation lever 64 urges the latter towards a rest position, shown inFIG. 13, in which the distance between the finger 181 of the lever 64and the release arm 177 of the pawl 162 is at a maximum. A thrust member185, in the form of a semicylindric flap rotatably mounted about theaxis A via mounting means which are not shown in the drawing, is locatedat a radial distance from the axis A which corresponds to that of thefinger 181 and of the arm 177 of the pawl. The finger 181 of theactuation lever engages a recess 187 of the flap such that a tilting ofthe actuation lever 164 causes a rotation of the thrust member 185toward the release arm 177 of the pawl 162 and, when the edge 189 of thethrust member 185 reaches the release arm 177, it compels the latter torotate, with the result that the tooth 171 at the other end of the pawl162 is moved out of engagement with the toothed sector 173 of the returncam. The sole holder 16 is then free to rotate in the opening directionas in the previous embodiments.

To obtain an automatic release of the pawl-type blocking arrangement 160beyond a certain rotation angle in the opening direction, in a mannersimilar to the embodiment of FIGS. 7 to 10, the base body 14 comprises asemicylindric upper extension 104, located at a radial distance from theaxis A substantially corresponding to the radial distance of the releasearm 177 of the pawl 162 and slightly less than the radial distance ofthe thrust member 185. This extension ends in an abutment edge 105located at a predetermined angle from the release arm 177, so that thelatter comes into contact against this abutment edge 105 when therotation of the sole holder 16 overcomes the predetermined angle, andthe tooth 171 of the pawl 162 comes out of engagement with the toothedsector 173 of the return cam 26 because of the resulting rotation of thepawl 162.

The recess 187 of the flap 185 is preferably a blind recess and the flapforms a closure member for the space between the base body 14, moreprecisely its abutment edge 105, and the sole holder 16 to prevent theingress of mud, snow or ice toward the interior of the device.

In addition, in this embodiment the tilting mechanism 106' is mounted inan inverted manner, i.e. its spring housing 108' is rotatably mounted onthe base body 14, while its spring abutment 110' is rotatably mounted onthe cage 163, or on the sole holder 16. This has the advantage toprevent the ingress of mud, snow or ice, which are practically alwayspresent in this lower area of the heel unit, towards the interior of thetilting mechanism 106'.

Finally, in order to reduce the play between the pawl 162 and thetoothed sector 173 of the return cam 26 when the tooth 171 of the pawlis not exactly engaged between two successive teeth of the toothedsector, the pawl 162 advantageously has two parts 162 and 162' mountedside-by-side on the same axis 191, as indicated in FIG. 14, and theirteeth 171, 171' are offset in the peripheral direction of the return cam26 by a distance which corresponds to half of the pitch of the teeth ofthe toothed sector 173 of the return cam. It is even possible togeneralize to any number N of pawls, the teeth of which will then besuccessively offset in the peripheral direction of the return cam by adistance corresponding to 1/Nth of the pitch of the teeth of the toothedsector.

What is claimed is:
 1. Heel unit (10) of a safety ski binding,comprising a base body (14) intended to be fixed to a ski (12), a returncam (26) rotatably mounted on the base body (14) about an axis (A) andreturned by a first spring device (28) into a rotary starting position,a sole holder (16) rotatably mounted about the axis (A), aunidirectional blocking arrangement (60) arranged between the return cam(26) and the sole holder (16) comprising at least one blockingarrangement (60), said blocking arrangement including at least oneblocking member for blocking said sole holder in an opening direction ofthe sole holder and said blocking member being releasable against theslight spring force of a second spring device (66) by means of a manualrelease lever (64), one of the return cam (26) and the sole holder (16)being provided with a bearing face (68), having a generally circularshape and being concentric to the axis (A) of the return cam and of thesole holder, for the blocking member (62) which is permanentlyresiliently urged into a blocking position between the return cam (26)and the sole holder (16), said blocking member (62) being supported in aforce-locked manner on the bearing face (68) when the sole holder isurged in the opening direction, and permanently engaging the bearingface (68) without force transfer when the sole holder is urged in aclosing direction, substantially independently of the actual rotaryposition of the sole holder (16) relative to the return cam (26), topermit a relative displacement of the sole holder (16) with respect tothe return cam (26) in the closing direction and substantially withouteffort.
 2. Heel unit according to claim 1, wherein the unidirectionalblocking unit (60) is realized as a frictionally-blocking arrangement(60').
 3. Heel unit according to claim 2, wherein thefrictionally-blocking unidirectional blocking arrangement (60'),comprises at least one blocking pawl as blocking member (62'), theblocking pawl (62') being pivotally mounted on the sole holder (16), thebearing face (68) being a substantially smooth semicylindrical surfaceprovided on the return cam (26), and the blocking pawl (62') being heldin contact against said bearing face (68) by means of a spring member(66) arranged between the blocking pawl (62') and the sole holder (16).4. Heel unit according to claim 2, wherein the frictionally-blockingunidirectional blocking arrangement is realized as a roller-typeunidirectional blocking arrangement (62) comprising at least oneblocking roller (62"), wherein the bearing face (68) is a substantiallysmooth semicylindrical bearing face provided on the return cam (26), andincluding a counter-surface (70) on the sole holder (16) formedeccentrically or planar and inclined with respect to a tangent (T) tothe bearing face (68) extending through a contact point (B) with theblocking roller (62") to define an intermediate space (72) which taperson one side in a wedge-like manner.
 5. Heel unit according to claim 4,including means for guiding the blocking roller (62") in contact withthe concentric bearing face (68) on a circular path (K) concentric tothe axis (A) of the return cam (26) and of the sole holder (16).
 6. Heelunit according to claim 4, wherein the blocking roller (62") comprises aceramic material, wherein a tangent of an angle (φ), between the Normal(N) to the bearing face (68) extending through a contact point with theblocking roller (62") and a connection line (D) of two contact points(B, C) of the blocking roller (62") with the bearing face (68) and withthe counter-surface (70), is equal to about 0.3.
 7. Heel unit accordingto claim 4, including at least two steel rollers (62") mountedsymmetrically with respect to each other, wherein a tangent of an angle(φ) between a normal (N) to the bearing face (68) extending through thecontact point with the blocking roller (62") and a connection line (D)of two contact points (B, C) of the blocking roller (62") with thebearing face (68) and with the counter-surface (70), is equal to about0.1.
 8. Heel unit according to claim 4, wherein the unidirectionalblocking arrangement (62) comprises at least one blocking roller (62"),includes a roller cage (80) rotatably mounted about the axis (A) of thecam and of the sole holder; wherein the cage (80) is fixedly coupled tothe sole holder for rotation therewith; wherein an intermediate space(70") which tapers on one side in the manner of a wedge is formedbetween the bearing face (68) and a counter surface (70") provided onthe roller cage (80) and receives a respective blocking roller (62");and wherein the blocking roller (62") which is guided on a circulartrack (K) concentric to the axis (A) of the cam and of the sole holder,is resiliently urged (74") into the blocking position.
 9. Heel unitaccording to claim 8, including at least two diametrically oppositeblocking rollers (62"); and wherein the blocking rollers (62") arerespectively accommodated in a respective intermediate space (72)located between the bearing face (68) of the return cam (26) and acounter-surface (70") of the roller cage (80).
 10. Heel unit accordingto claim 8, including a release lever (64") pivotally mounted on thebase body (14) about the axis (A) of the cam and of the sole holder, theblocking roller being mounted on the release lever, whereby theroller-type unidirectional blocking arrangement (60") can be released bya corresponding displacement of the blocking roller (62") with respectto the roller cage (80).
 11. Heel unit according to claim 10, includingmeans for resiliently holding the release lever (64") in a startingrotary position with respect to the roller cage (80), in which theblocking roller (62") occupies its blocking position.
 12. Heel unitaccording to claim 10, wherein the sole holder (16) is extended by alever arm (120), the release lever (64") being arranged inside the soleholder (16) and being accessible from the exterior.
 13. Heel unitaccording to claim 1, wherein the unidirectional blocking arrangement(60) includes a pawl-type unidirectional blocking arrangement (160)comprising at least one pawl (162) pivotally mounted on the sole holder(16) and ending on one side in a tooth (181) oriented towards the returncam (26); the bearing face (68) of the latter comprising a correspondingtoothed sector (173); and means resiliently urging the pawl (162) insuch a manner that the tooth (181) comes into engagement with saidtoothed sector (173).
 14. Heel unit according to claim 13, wherein thepawl blocking arrangement comprises at least two pawls (162, 162"); andwherein the teeth (181, 181') of said pawls are successively offset in aperipheral direction of the return cam (26) by a distance whichsubstantially corresponds to a pitch of the teeth of the toothed sector(173) of said return cam (26), divided by the number (N) of pawls (162,162').
 15. Heel unit according to claim 13, including a release arminclined with respect to a radial direction from the common axis (A) ofthe return cam (26) and the sole holder (16) and extending each pawl(162) on the side remote from the tooth (181) and wherein the base body(14) comprises an abutement (105) located at a predetermined angle withrespect to said release arm (177) when the sole holder (16) occupies aclosing position such that, when the rotation of the sole holder (16)exceeds said predetermined angle, said release arm (177) engages saidabutement (105) and the tooth (181) of the pawl (162) comes out ofengagement with the toothed sector (173) of the return cam (26)following the pivoting of the pawl (162) resulting therefrom.
 16. Heelunit according to claim 15, further comprising a manual actuation leverpivotally mounted on the sole holder (16) and resiliently returned to arest position, and a thrust member (85) pivotally mounted on the basebody about the common axis (A) of the sole holder (16) and of the returncam (26), said thrust member (185) being driven by said actuation lever(64) and having an edge (189) directed towards the release arm (177) ofthe pawl (162), said edge (189) being able to come into engagement withsaid release arm (177) when the manual actuation lever (164) is pivotedaway from its rest position.
 17. Heel unit according to claim 16,wherein said thrust member (185) has the shape of a semicylindrical flapand constitutes a closure for an opening between said base body (14) andsaid sole holder (16).
 18. Heel unit according to claim 1, including amanual actuation lever (64) pivotally mounted on the base body (14)about the axis (A) of the return cam (26) and of the sole holder (16),said manual actuation lever being provided for pivoting said sole holder(16) at least in the opening direction.
 19. Heel unit according to claim1, including release means for the unidirectional blocking arrangement(60), and means for actuating said release means independently of amanual actuation lever (64) coupled to the sole holder (16).
 20. Heelunit according to claim 1, including a manual actuation lever (64)coupled to the sole holder (16) for releasing the unidirectionalblocking arrangement (60), at least one drive member (76) on the manualactuation lever (64) for driving the sole holder (16) with a delay inthe opening direction after release of the unidirectional blockingarrangement (60), a spring coupling the manual actuation lever (64) andthe sole holder (16) and holding the latter in a starting relativeposition in which the unidirectional blocking arrangement (60) is notyet released, the sole holder including at least one opening (78) andsaid driving member (76) engaging the at least one opening (78), thesize of the opening being larger than a cross-section of the drivingmember (76) received in the opening (78) in a manner to thereby definethe driving delay.
 21. Heel unit according to claim 1, comprising amanual actuation lever (64) including a driving member (76) forreleasing the unidirectional blocking arrangement (60), a blocking pawl(62') of the unidirectional blocking arrangement (60) covering anopening (78) through which the driving member (76) extends as far as,when the manual actuation lever (64) is urged in the opening directionby the driving member (76), the blocking pawl (62') is initially liftedfrom the bearing face (68), and the sole holder (16) is thereafterdriven.
 22. Heel unit according to claim 21, wherein the blocking roller(62") of the unidirectional blocking arrangement (60) comprises aroller-type unidirectional blocking arrangement (60") connected to themanual actuation lever (64) which is pivotable about the axis (A) of thereturn cam and of the sole holder and is coupled to the sole holder (16)by means of the spring member (74).
 23. Heel unit according to claim 1,further comprising a release arrangement (64", 86, 102, 104) associatedto the unidirectional blocking arrangement (60) and activated as afunction of the rotary position of the sole holder (16), the releasearrangement releasing said unidirectional blocking arrangement (60) in aforced manner when the sole holder (16) reaches a rotary position withina rotation range limited by a release position for the ski boot and bythe opening position.
 24. Heel unit according to claim 23, wherein saidrelease arrangement (64", 86, 102, 104) comprises a release piston (86)which is guided on the sole holder (16) and biases the release lever(64"), the piston cooperating with a climbing ramp (102) provided on thebase body (14) and with a partly cylindrical surface portion (104) ofthe base body (14) which follows said ramp and is concentric to the axis(A) of the return cam and of the sole holder.
 25. Heel unit according toclaim 1, wherein the return cam (26) urged by the first spring device(28) has a control surface (46) devoid of a culminating point so thatthe first spring device (28) constantly urges the return cam toward thestarting position corresponding to the closing position independently ofthe actual rotary position of the return cam (26).
 26. Heel unitaccording to claim 1, wherein the return cam (26) comprises a partlycylindrical portion (44) having a flat control surface portion (46) onwhich rests a piston-shaped supporting abutment (40) of the first springdevice (28) when the return cam (26) is not urged by the sole holder(16).
 27. Heel unit according to claim 1, including a tilting mechanismurging the sole holder (16) toward the opening direction separately fromthe return cam (26) as long as the sole holder occupies a rotaryposition between its opening position and a predetermined intermediateposition; and wherein the tilting mechanism (106) urges the sole holder(16) toward the closing direction as long as the sole holder occupies arotary position between its closing position and said predeterminedintermediate position.
 28. Heel unit according to claim 27, wherein thetilting mechanism (106) comprises a toggle mechanism.
 29. Heel unitaccording to claim 28, wherein the toggle mechanism (106) comprises aspring housing (108), a spring (112) mounted in the latter, and a springabutment (110, 118) axially slidably mounted in the spring housing(108).
 30. Heel unit according to claim 29, wherein the spring housing(108) is pivotally mounted on the base body (14) about a transverse axis(G), and in that the spring abutment (110) is pivotally mounted on thesole holder (16) about a transverse axis (H).